The Public Switched Telephone Network (PSTN) is the backbone for providing telephony services to business and individuals in the United States. The PSTN includes a number of switches, generally designated as Service Switching Points (SSPs), for interconnecting a calling party's line to a called party's line. Prior to the 1960's, to complete a call between a calling party and a called party, signaling would occur over the trunk circuits between the switches to ensure that the called party was not busy and to establish a connection between the two parties. This earlier version of the PSTN was rather inflexible in that changes to the PSTN could only occur with the replacement of the hardware in the PSTN. For instance, at this time, the SSPs were hard-wired and had to be replaced with a new SSP in order to update the switch's capability. The switches, however, could not be quickly updated since the standards and specifications had to be well-defined for the various switch vendors. To address the delays in updating switches, these hard-wired SSPs were ultimately replaced with SSPs that had stored program control (SPC). As a result, rather than replacing an entire SSP, the SSP could be modified to enable a new feature simply by updating the software in the SSP. Even with SPC in the SSPs, the PSTN was still limited in the services that the PSTN could provide.
A major advancement to the PSTN occurred in the mid-1970's with the introduction of Signaling Transfer Points (STPs) and Signaling System number 7 (SS7) protocol. With the addition of SS7 and STPs to the PSTN, call setup information is routed over a signaling network formed between the STPs and no longer occurred directly over the trunks. For instance, a calling party's SSP would send a data query from one of its associated STPs to an STP associated with the called party. The called party's STP would then determine whether the called party's line was idle and would perform the necessary signaling over the SS7 data network to connect the call. Thus, whereas before call setup signaling would occur over the voice trunks, the STPs and SS7 signaling bypass this traffic away from the voice trunks and onto dedicated data lines. As a result, the capacity of the PSTN to carry voice calls was greatly increased.
In the mid-1980's, demand for additional services from the PSTN resulted in the Intelligent Network. In general, the Intelligent Network provides service logic external to the SSPs and places this logic in databases called Service Contact Points (SCPs). To accommodate in the Intelligent Network, the SSPs have software to detect service-specific features associated with the Intelligent Network. The software in the SSPs define hooks or “triggers” for the services that require use of an SCP. In response to a trigger, an SSP queries an associated SCP for relevant routing information. For instance, the Intelligent Network permits 800 service and calling card verification service, both of which require a query from the SSPs to the SCP through an STP and the return of routing information to the SSP through an STP. A Service Management System (SMS) was also introduced into the PSTN with the Intelligent Network and provides necessary support in service creation, testing, and provisioning. The SMS communicates with the SCPs and provides software updates to the SCPs.
The demand for increased capabilities has more recently transformed the Intelligent Network into an Advanced Intelligent Network (AIN). The AIN differs from the Intelligent Network in that the AIN provides service independent capabilities whereas the Intelligent Network was limited to service-specific capabilities. AIN provides a high level of customization and builds upon basic services of play announcement, digit collection, call routing, and number translation. Some examples of AIN services include abbreviated dialing beyond a central office, do not disturb service for blocking calls from certain numbers or at certain times, and area number calling service which allows a company to have one advertised telephone number but to have calls routed to a nearest business location.
In recent years, the explosive growth of the mobile industry as well as new products such as prepaid services have placed ever increasing demands on the Intelligent Network. Examples of services for which there is a need to implement in the Intelligent Network include Location Based Services such as location based advertising or wireless 911, prepaid wireless and wireless callbacks.
FIG. 1 provides a simplified diagram of the architecture of an exemplary Intelligent Network. Subscriber Equipment SE 110, such as a telephone, a mobile station, a computer, or a fax, for example, is connected via a first signaling network 118 to a SSP 102 or via a Network Access Point NAP. The SSP 102 provides the user with access to the network and attends to all necessary dialing functions. The SSP is also able to detect the need for an Intelligent Network service request. In functional terms, the SSP includes call management, routing, and service dialing functions. Furthermore, SSPs are capable of communicating with other SSPs 112 across the first signaling network 118. It is noted that appropriate switching network protocols include SS7 protocols, such as global system for mobile communications (GSM) and code division multiple access (CDMA), or data network protocols, such as general packet radio service (GPRS), universal mobile telephone system (UMTS) and 1XRTT (also known as CDMA2000). The SSPs 102 communicate using a second signaling network 104 with at least one of the SCPs 106, which include Service Logic Programs SLP, which are used to produce network services. Thus, the SCPs 106 are capable of communicating with switches in appropriate protocols (e.g. INAP, WIN) for setting up triggers, accepting trigger events, and responding with instructions. It is noted that the second signaling network 104 is also used to switch calls.
Each SCP is optionally connected to one or more Service Data Points (SDP) 108. The Service Data Point SDP 108 is a database containing such data about the subscriber and the Intelligent Network which the SCP service programs use for producing individualized services. The SCP uses SDP services directly by way of a signaling or data network.
The optional Intelligent Peripheral IP 114 provides special functions, such as announcements, and voice and multiple dialing identification.
One exemplary protocol commonly used in the second signaling network is SS7, a known signaling system described in the Specifications of Signalling System No. 7 of the CCITT (nowadays ITU-T), Melbourne 1988.
Thus, in the course of operations a SCP 106 routes a plurality of requests to establish triggers over the second signaling network 104 to one or more SSPs 102. Triggers correspond to specific or general event detected at the switch 102, including the dialing of a toll-free number such as a ‘800’ number, a call reaching subscriber with a particular number, the dialing of a specific number starting with ‘011’ by a particular subscriber, an off-hook event, a mobile subscriber entering a specific cell region, and so on. Whenever an event matching the conditions of the trigger is detected at the switch 102, the switch 102 stops, sends a message over the second signaling network 104 informing an SCP 106 of the event, and awaits instructions, which are routed back to the SSP 102 over the primary signaling network 104. Examples of instructions that the SCP 106 sends to the switch 102 include commands to continue as normal, terminate the call, transfer the call to a particular subscriber, transfer the call to an “Intelligent Peripheral” (IP)—which may play a prompt, collect dialed digits, etc.
FIG. 2 provides a simplified flow chart describing the aforementioned event handling mechanisms from the perspective of the switch 102. In general, the switch (SSP) 102 operates 206 according to a set of triggers which have been set 204 according to instructions 202 received over the second signaling network 104 from an SCP 106. When, in the course of operation an event transpires, the SSP must handle the event 208. Block 210 indicates that if the event does not match any of the triggers, the switch 102 proceeds to operate 204 as before, but if the event does match a trigger, the switch 102 must inform 212 the SCP 106 of the event, where this information is communicated over the second network 104. The switch 102 then waits 214 for a response from the SCP 106, which is sent to the switch 102 over the second signaling network 104. Upon receiving the instructions 216, the switch 102 responds to the event 218, and reverts to normal operating mode 206.
This aforementioned architecture presents a myriad of possible problems. First of all, it is noted that the SCP 106 and the switch (SSP) 102 communicate through the second signaling network 104, which is part of the primary signaling network (mostly the SS7 network). This network is a most critical network inasmuch as it is responsible for the most basic services of the network: switching calls. When Intelligent Network communication is excessive, it can harm or even overwhelm the signaling network. This is considered risky, and potential outages are unacceptable.
Furthermore, the need for the switches 102 (SSP) to handle triggers imposes an additionally processing load on the switch itself. Once again, this is unacceptable because the switch 102 is also responsible for switching calls. If these triggers are few or only pertain to a small number of events, then this load is insignificant. But, many applications require setting up triggers for large groups of subscribers, and for widespread events. For example, pre-paid wireless subscribers applications require a trigger for each and every call the subscriber makes, as well as a periodic trigger in order to verify at each stage that the subscriber has the appropriate positive balance to proceed with the call. Location based services, which require the location of each subscriber of a cellular network, are implemented by setting up a trigger for the event of a subscriber moving from one cell to another. As the volume is Intelligent Network services offered subscribers increases, the number of triggers increases, concomitantly increasing the load imposed upon the SCP 106 which creates the triggers, the switching network 104 which communicates the triggers, and the switch 102 which identifies events that satisfy the conditions imposed by the triggers, and handles the responses to the triggered events.
It is noted that the aforementioned problems are exacerbated by the current trends wherein carriers are continually extending the portfolio of specific services they offer to customers, especially mobile services.
One approach for handling overloaded switches and/or signaling networks is simply to add extra network capacity, including switches with more CPUs, more powerful CPUs and more memory, as well as switching equipment to bolster the primary switching network. One diagnostic approach is the deployment of load measuring means, usually signaling probes capable of passively observing switches as well as other primary signaling network components in order to detect the load on the switch and/or signaling network. Knowledge of component overload is then relayed to the appropriate authorities in order to repair and/or upgrade overloaded networks.
U.S. Pat. No. 5,726,972 discloses a monitor probe for a communications signaling network, such as an SS7 network, arranged to determine its own location on the signaling network by watching for a particular type of message which carries the required information in its routing label.
U.S. Pat. No. 6,295,351 discloses method and system to invoke a check of a service package application (SPA) with respect to a communication as the communication is routed through the telecommunications system.
U.S. published patent application 2001/0019606 discloses a method of controlling service execution in an Intelligent Network, including at least one switching point (SSP) and several service programs (SLP).
U.S. published patent application 2002/0034190 discloses a system that uses Idle cellular resources for voice and data services.
U.S. published patent application 2004/0013251 discloses a communication interface between pc's and auxiliary platforms in an Intelligent Network There is an ongoing need for apparatus and methods for enabling the SCP and SSP to provide Intelligent Network services using fewer system resources, obviating the need for expensive switch upgrade or capacity expansion in order to provide more Intelligent Network services. Preferably, the apparatus and methods also enable a load reduction on the primary signaling network which is responsible for switching calls. There is an ongoing need for a more robust Intelligent Network architecture, where more Intelligent Network tasks are performed using components not responsible for primary network functioning.